Method for forming sand-molds



June 24, 1930. STONEY 1,768,429

METHOD FOR FORMING s mpuouns Filed Aug. 16} 1924 2 Sheets-Sheet 1 JTJ";

June 24, l93 0.- J. 'r. STONEY METHOD FOR FORMING SAND MOLDS Filed Aug;16, 1924 2 Sheets-Sheet 2' Iva/e77 Z- Patented June 24, 1930 rs 'r' etes JOHN T. STOREY, F CLEVELAND, OHIQ M rnon FOR romainesaim-MoLDsApplication filed August-16, 1924. Serialso. 722,358.

This invention relates to a" method and apparatus tortorming molds,cores and similar devices from sand or any material which is analogousior the purpose. Theprincipal object of the invention is to providemethod and apparatus whereby the material ofwhich a mold or core ismade, as for instance sand, may be readily compacted ,in the flask orbox in which the mold or core is made, by imparting in a suitablemanner, to the, flask,'a series of percussive impulses impartedsuccessively, which'act' upon the sand or analogous material to cause itto settle. k q A further object of the invention is to impart thepercussive impulses of the sand in one direction only and this directionof application being such as to cause the sand to settle and compact ina minimum space of time. I

I am aware that it is common in the molding art to prepare molds of sandand compact the sand by jarring the sand in a flask, around a pattern.'This arring method has proven' quite satisfactory in the art, but thenew method herein proposed has many dis-' tinct advantages over thejarring method? towhich reference has been made.

In the arring method of compacting sand in molds, the table ofa moldingmachine and mold thereon is elevated and then dropped. The jarring takesplace when the table reaches the end of its downward move ment and thear lmparted 1 s momentary.

Subsequent tothe jarring the table is raised.

to its upper limit of movement, then released and moves by gravity toits low limit of movement. Therefor there is between sue cessiveimpulses or impacts in the jarring method a period of rest in which thesand is quiescent, In other words, the sand is jarred and is moved tocause the settling of the sand only at the time of impact and betweenthe impacts there are periods when there is no movement of the sand.

In the proposed method of molding, a great number of impacts per unit oftime, by use of a vibrator or similar mechanism, is given to the tableon which the flask is supported.

possibly-be accomplished with the jarring The impacts are suflicientlyfie quent so; that thesand is continually in agitat onduring the periodof compacting, and the particles 0t sand in movement, seek to find themost advantageousand compacted relation with respect to adjacentparticles of sand. i It will, of course, be apparent that mediapact-sdelivered to a flask or the table upon which the flask is placed, in themaking of a mold, must be sufficiently heavy to accomi pl'ish thepurpose which, has been "described and I'say this'to distinguish mypresent inventionfrom thecommon practice of, using a small vibratingmachine, which is used' during a drawing operation to secure a goodparting between the pattern and the mold, such a vibrator beingusedsometimes'in con.- nection with a pattern plate, or being connecteddirectl'yjwith a fiask or the table upon which the flask rests. 1 v 7Furthermore, as before stated, in the sand compactingope'rati'on, Iemploy a series' ot rapidly recurringjimpacts, in one direction 7 only,as for instance, impacts against the under side'ot a table upon which aflask or sand thereinrrests, whereby such blow imparted, causesagitation of the sand withtheultimate effect of causing it to settlemore compactly within the'fiask. 'lhedift'erence in action between thevibrating method and the jarring method, in compacting OI: sand inamold, produces the, resultthat' the vibrated mold is compacted in a muchshorter period of time than could method of compacting sand. Forinstance," on making the cope or drag half of a four cylinder automobileengine mold, the sand by the vibrating method will be compacted in aperiod; of time vapproximating one second, whereas the same mold made ona jarring machine would require a jarring operation during a period ofsome eight seconds.

1here is another and equally important advantage gainedby the vibratingmethod and that is that the sand is compacted much more uniformlythroughout all portions'ofthe fiask than is possible to obtain'with the'arrin method of makin molds. m9 1 z: 2::

Furthermore, I have found that with the vibrating method it is quitepossible to use flasks in which the cross bars or plates are dispensedwith. In other words, a flask may be employed Without the use of bars orplates to support the sand when compacted within the flask. In thejarring method the use of bars or plates for supporting the sand andholding it in the flask is absolutely essential.

Another advantage in the method is the saving of time in making the moldduev to the fact that in the vibrating method of making the mold it isnot necessary to sieve the sand onto the pattern before shoveling in thelarge bulk of sand which forms the body of the mold within the flask.Vith the proposed method any sand that is at all suitable for molds maybe used and it may be directly shoveled into the flask without previoushand sieving. This is a distinct saving in time.

Additionally, it is found that in the majority of cases. at least it isnot necessary to use a stripping plate, even with a pattern which isquitecomplicated, or, to state it another way, it is possible in manyinstances to omit the use of a stripping plate when making the mold bythe Vibrating process where, under the same'eonditions,in making thesame mold by the jarring process it would be absolutely impossible to dowithout the stripping plate.

The advantages which are gained by the vibrating method of making moldsare, therefore, very pronounced and certain and I attribute theseresults to the entirely different action obtained in the vibrating ofthe mold as distinguished from the jarring of the mold; that is to say,maintaining the sand in an agitated condition with the grains of sandfree to move with respect to adjacent grains of sand during the entirecompacting operation, as distinguished from the intermittent compactingoperation which is incident to the making of molds by the jarringmethod. 7

All of these improvements which have been discussed have a very decidedeffect upon the cost of making molds, not only in the matter of lowerlabor costs and the ability to produce more molds per unit of time, butalso better molds, better compacting and less likely to require patchingup.

In quantity production of castings, the saving of time and labor is avery important item.

Reference should be had to the accompanying drawings forming a partofthis specification in which Fig. l is a side elevation of the apparatusemployed in forming sand molds which consists of a flask supportingtable and a fluid operated vibrator by which percussive impulses areimparted through the table to the mold part supported thereon; Fig. 2 isa top plan view of the table; Fig. 3 is a fragmentary side elevationshowing a.

flask containing sand mounted on the table; Fig. 4 is a vertical sectiontaken axially of the vibrator; Fig. 5 is an end View of the vibratorwith a portion broken away to show the exhaust ports in section; Fig. 6is a side elevation of-the piston or striker; Fig. 7 is a sectionalelevation showing a modified form of flask supporting table.

Referring to the accompanying drawings, which embody the best way ofcarrying the invention into effect, as far as I now know, the flasksupporting table consists of a top 1 which has a flat top surface toreceive the flask and which is preferably in the form of a casting withdownwardly projecting reenforcing ribs 2 onits under side which radiatefrom a central thickened impact receiving portion 3. The table top 1 maybe rigidly supported, as shown in Figs. 1, 2 and 3 or yiel'dablysupported as shown in Fig. 4. In Figs. 1, 2'and 3 the table is shownrigidly supported upon legs 4 which project upwardly from a supportingstand 5 which is rectangular in form and which is preferably formed oftwo castings each provided with base flanges 6 adapted to be bolted orotherwise rigidly secured to the floor, the castings being detachablyconnected by bolts 7. Mounted within the stand 5 and rigidly securedthereto is a vertically disposed fluid pressure operated vibrator whichhas an outer cylindrical casing 8 which is open at its upper end and inwhich is mounted the reciprocating piston or striker by which percussiveimpulses are im parted to the table. Within the casing 8 there is aninner cylinder 9 which is closed at its lower end by a bottom plate 10which bears against the integral lower end of the casing 8. The innercylinder 9 is held in place within the casing 8 by means of a topclosure member 11 which bears against the upper end'thereof and issecured to the casing by means of tap bolts 12. The cylinder 9 is heldagainst rotation within the casing 8 by means of a screw stud 13 whichis screwed into a threaded opening in the outer casing 8 and projectsinto an opening in the inner cylinder. Extending through the closuremember 11 at the center thereof is a percussion member l l which has asubstantially fluid tight fit in the closure member but is not securedthereto and projects beyond the inner face thereof to receive the impactof the piston. At its upper end the percussion member 14 has an enlargedhead 15 which bears upon the upper surface of the closure member 11 andagainst the bottom of the thickened portion 3 ofthe table top 1. Withinthe cylinder there is mounted a piston or striker 16 which has twospaced peripheral grooves forming three spaced circumferential flanges17, 18 and 19 which are of the same diameter and have a sliding fitwithin the inner cylinder 9. Between these Hill flanges the annulargrooves formi-with the v'vall of the cylinder 2 annular chambers of, theopen end of the bore being closed by a screw plug 25. The inlet chamber24 communicates with. the interior of a cylinder through twolongitudinally spaced ports 26 and 27 which are so spaced that as thepiston reciprocates they are alternately opened and closed by theflanges 17 and 19 and are placed alternately into communication with theannular chambers 20 and 21 to move the piston in opposite directions.Air under pressure is supplied to the inlet chamber 24 through an inletpipe 28 which extends through the wall of the casing and communicateswith the chamber, the supply of pres- 1 sure to the cylinder beingcontrolled by a valve (not shown) in the pressure supply line as wellunderstood in the art. An annular exhaust chamber 30 surrounds the innercylinder 9 substantially midway between the ends thereof, the chamber 30being formed by complementary grooves formed in the inner surface of theouter casing and the outer surface of the inner cylinder. Communicationbetween the interior of the cylinder and the exhaust chamber isestablished through either of two parallel circumferentially extendingrows of exhaust ports 31 and the air escapes from the exhaust chamberthrough an exhaust pipe 32 which is attached to the outer casing andcommunicates with the exhaust chamber adjacent the ports 31. The tworows of ports 31 are so positioned that as the piston moves past theports pressure is exhausted alternately from opposite sides of thepiston so that as pressure is admitted to one side of the piston, air ispermitted to escape from the opposite side. Whenever the supply ofpressure tothe cylinder is cut off the piston drops to the lower end ofthe chamber where it is so positioned with respect to the inletandexhaust ports that it will be operated upon admission of pressure tothe cylinder. Once the piston is started it will continue to reciprocateas long as pressure is supplied to the cylinder due to the automatlcreversal of pressure by the movement of the piston past the ports;

3 air pressure-supplied through; an inlet pipe .35 which communicateswith thechamber 36 between the" plunger andbottom plate 10 through aport37 adjacent the bottom plate, the chamber 36 preferably containing abody of liquid such as oil. -The plunger 3 is cup shaped and has adownwardly extending skirt or flange 38. which serves to guide theplunger. As thepiston impingesagainst the plunger 33, the plunger ismoved slightly, but the air and oil behind the plunger quickly absorbthe impact- The vibrations caused by theimpact of the piston 16 againstthe plunger 33 are entirely taken up'and dissipated by the fluid cushionso that the onlyvibrations transmitted to the table are those due to theimpact of the piston 16 against the percussion memberld. There issufficient {working clearance between the plunger and the "wall of thecylinder to permit small quantities of oil to be forced past the plungerinto the main chamber'of the cylinder to lubricate the piston; Some-airwill'leak' past theplu-ng er when th'e'vibrator is not in operation butthe weight of the piston is suliicient to overcome the leakage pressure.u

in forming a sandmold,:a-flask 39; or other container in which themold-is to beoformed is placed upon thetable 1 as shown in Fig. K

sand, a weight 41 which fits within. the

frame 40 is preferably laid uponthe top of the sand and-followsthe sanddownwardly as the sand is'compacted in the flask. The packing of thesand in the flask is accomplished by admitting 'l-uid pressure to thevi.- brator cylinder which causes the piston-16 to reciprocate 1 rapidlyand to impart sharp percussive impacts in rapid successiontothepercussion memberll. The vibrationsdue tothese impacts aretransmitted through the table land flasks 39t'o, thesand within theflask, The impulses imparted tothe par= 'ticles of sand are all in anupward direction since all; vibrations in the framework except those dueto the impact of the pistonhin' anv upward direction against thepercussion member are eliminated by the fluid CHShlOII'w' ing device atthe bottom of the cylinder. These rapidly succeeding impulses in'anupward direction cause the sand to rapidly I settle and form itself intoa compact massand the packing action is materially hastened due to thefact that all of the percus.

weight acting as a follower prevents disturbance of the sand at the topof the flask and causes the sand to settle evenly and to pack uniformlythroughout the entire mass.

In Fig. 7 there is shown a modified form of flask supporting table inwhich the top or flask support 1 which is similar in construction to thetop 1 above described is yieldably supported upon the upper end of posts4*. The top 1 is connected to the upper end of the posts by bolts 42,which extend through the table and through flanges 43 at the upper endsof the posts. The bolts 42 have nuts 44 at their lower ends andinterposed between the nuts and underside of the flanges 43 are coilspirngs 45 which serve to yieldably hold the plate upon the posts andpermit a slight upward movement of the flask support upon impact of thepiston.

It will be understood that the invention is equally applicable to themaking of cores and in referring to the molds, I include cores, andfurther in the use of the term sand in the specification and claims, Iintend this use in a generic sense and to include other materials whichwould function in the same manner so far as concerns the method hereindisclosed.

Having described my invention, I claim:

1. The method of forming sand molds or cores which comprises placingsand within a flask or box and subjecting the flask or box to a seriesof rapidly recurring impacts, in one direction only, thereby to causethe sand to settle in the flask or box.

2. The method of forming sand molds or cores, which comprises placingsand within a flask or box, placing pressure upon the top ofthe sand andsubjecting the flask or-box to a series of rapidly recurring impacts, in

one direction only, thereby to cause the sand to settle within the flaskor box. 7

3. The method of forming sand molds or cores, which comprises placingthe sand within a flask or box, placing a weight upon the top of thesand and subjecting the flask or box to a series of rapidly recurringimpacts, in one direction only, to cause the sand to settle in the flaskor box.

4. The method of forming sand molds whichcomprises supplying a flaskwith sand and imparting thereto a series of percussive impulses in rapidsuccession and in one direction only.

5. The method of forming" sand molds which comprises supporting a flaskcontaining sand upon a supported table, and imparting to said table aseries ofpercussive impulses in rapid succession and in an upwarddirection only.

6.The method of forming sand molds which comprises supporting a flaskcontaining sand centrally upon a table, and imparting to the tabledirectly beneath the flask a series of percussive impulses in rapidsignature.

JOHN T. STONEY.

